Updated at 10:39 p.m.

Brian Williams, the NBC Nightly News anchor, has acknowledged he was not aboard a helicopter that was hit and forced down by enemy fire during the U.S.-led invasion of Iraq in 2003. It's an about-face for Williams and the network, which for years claimed the anchor was aboard the chopper.

Williams' admission and apology was reported by Stars And Stripes.

"I would not have chosen to make this mistake," Williams told the newspaper. "I don't know what screwed up in my mind that caused me to conflate one aircraft with another."

In a post on Facebook, Williams wrote:

"I feel terrible about making this mistake, especially since I found my OWN WRITING about the incident from back in '08, and I was indeed on the Chinook behind the bird that took the RPG in the tail housing just above the ramp. Because I have no desire to fictionalize my experience (we all saw it happened the first time) and no need to dramatize events as they actually happened, I think the constant viewing of the video showing us inspecting the impact area — and the fog of memory over 12 years — made me conflate the two, and I apologize."

Williams, the newspaper said, most recently made the claim about being on the helicopter last Friday when presenting his network's coverage of a tribute to a retired soldier who provided security for grounded helicopters.

"The story actually started with a terrible moment a dozen years back during the invasion of Iraq when the helicopter we were traveling in was forced down after being hit by an RPG," Williams said on the broadcast. "Our traveling NBC News team was rescued, surrounded and kept alive by an armor mechanized platoon from the U.S. Army 3rd Infantry."

But Stars And Stripes adds: "The NBC anchor was nowhere near that aircraft or two other Chinooks flying in the formation that took fire. Williams arrived in the area about an hour later on another helicopter after the other three had made an emergency landing, the crew members said."

The newspaper quoted an Army sergeant as saying Williams and his NBC team were actually aboard a Chinook that took no fire but did land. NBC later provided a quote from a 2003 Williams segment that appears to confirm that: "On the ground, we learn the Chinook ahead of us was almost blown out of the sky."

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